Stroke is one of the leading causes of death in the U.S., but what else do you know about it?

For instance, did you know that someone has a stroke every 40 seconds? Dies of stroke every 4 minutes?

"Stroke is common, but that's not all people need to understand about it," says Dr. Akhila Vijayakumar, a neurologist at Houston Methodist. "We also want people to be able to identify stroke, in themselves or other people, as well as to know the urgency and time-sensitive nature of stroke treatment."

Dr. Vijayakumar also points out that stroke isn't just something that affects the elderly. Its prevalence in younger adults has been rising in recent years. In other words, it's something everyone should be knowledgeable about and take seriously.

Dr. Vijayakumar answers some common questions about stroke below.

What is a stroke?

"Stroke is a sudden interruption of blood supply to the brain, occurring either due to blood vessel blockage or rupture," explains Dr. Vijayakumar. "This is a problem because the neurons and tissue in the brain need a steady supply of blood in order to receive the oxygen and nutrients needed to function optimally and survive."

When the brain goes without blood for a sustained time, neurological damage ensues. This makes stroke a medical emergency. If treatment is delayed, permanent brain damage can result. It's why stroke is one of the leading causes of disability in the U.S.

"The sooner we can intervene and restore blood flow to the brain, the lower the risk of loss of function or disability in the future," says Dr. Vijayakumar.

"This isn't a medical concern where you simply call your doctor's office to make an appointment," emphasizes Vijayakumar. "Stroke necessitates immediate medical attention. It's an emergency that requires dropping whatever it is you're doing and calling 911. Every minute counts."

What causes a stroke?

"There are several risk factors of stroke, and sometimes more than one factor can influence a person's risk," says Dr. Vijayakumar.

Stroke risk factors include:

• High blood pressure (hypertension)
• Type 2 diabetes
• High cholesterol
• Atrial fibrillation (AFib)
• Sleep apnea
• Smoking
• Physical inactivity

"Diabetes as a stroke risk factor is especially important in younger people and women," says Dr. Vijayakumar. "And atrial fibrillation, which is a type of abnormal heart rhythm, is an important risk factor in the elderly, especially older women who are at higher risk for having a stroke due to atrial fibrillation."

Treatment of stroke risk factors can help reduce risk. If you have any of the health conditions above, work with your doctor to stay on top of your health and ensure any underlying health issues are well managed.

Dr. Vijayakumar notes that a few of the factors above are modifiable.

"Smoking is a major risk factor, increasing a person's risk of stroke by three to four times. Stopping smoking can greatly reduce your stroke risk," explains Dr. Vijayakumar. "Lack of physical activity leads to worsening of the health issues mentioned above, so it's important to avoid a sedentary lifestyle."

Ischemic vs. hemorrhagic: How do the types of stroke differ?

There are two main types of stroke:

• Ischemic stroke – when a blood vessel supplying the brain becomes blocked
• Hemorrhagic stroke – when a blood vessel supplying the brain ruptures, leading to bleeding in the brain

"Ischemic stroke is the more common type, but both types are medical emergencies," adds Dr. Vijayakumar.

How do I know if I am having a stroke?

Stroke is a medical emergency, so being able to quickly recognize sudden onset of neurological changes in yourself or someone else is critical.

Fortunately, there's an acronym to help remember the signs of stroke, BE FAST:

• B is for balance. Is there a sudden change in a person's steadiness, such as dizziness or difficulty walking?
• E is for eyes. Is there a sudden onset of vision changes or vision loss?
• F is for face. Is the person's smile uneven? Check by asking them to smile.
• A is for arms. Is there weakness or drooping in an arm on one side? Check by asking the person to hold out their arms.
• S is for speech. Is speech slurred or incoherent?
• T is for time. When did the changes start? In terms of stroke treatment, time is critical, so it's very important to note when the person was last in their normal state.

"If you notice stroke symptoms in yourself, a family member, friend, coworker or even a stranger, call 911 immediately," emphasizes Dr. Vijayakumar.

What should you do if you notice the symptoms of stroke?

When it comes to responding to stroke symptoms, Dr. Vijayakumar uses the phrase emphasizing the need for prompt intervention: "Time is brain."

That is, if you or someone around you is exhibiting signs of stroke, call 911 immediately.

"With every minute that passes after a large vessel stroke, 1.9 million neurons die," warns Dr. Vijayakumar. "This is why it's incredibly important to get to the emergency room to receive treatment as soon as possible. If stroke symptoms arise, do not delay."

The stroke treatment options available are also time sensitive. In the first 4 1/2 hours from just before the onset of symptoms, clot-busting drugs can be used to help restore circulation. Also in that time period, endovascular procedures can be performed to retrieve the clot blocking blood flow in certain cases. This is why you shouldn't wait to see if symptoms get worse or until you can speak to your doctor.

Beyond about 6 hours, Dr. Vijayakumar says that the options to restore blood flow diminish greatly and outcomes begin to decline.

"I do want to emphasize that, although we have this 4 1/2-hour window to provide these treatments, it's not ideal to wait that long," reiterates Dr. Vijayakumar. "Remember, every minute that passes without treatment, neurons are lost. The earlier we can intervene, the better the chance of preventing permanent brain damage that causes disability."

Calling 911, rather than trying to drive to the emergency room, is a critical point. You should never try to drive if you're experiencing stroke symptoms yourself, but even if you notice the signs in someone else, still call an ambulance.

"EMS professionals are trained to handle emergencies and can get you to the emergency room faster and more safely, which means quicker treatment," adds Dr. Vijayakumar. "They can also inform the hospital ahead of time, so that ER doctors and nurses are prepared to receive an individual with stroke, further reducing time to treatment."

Are there ways to prevent stroke?

As hard as it is to make healthy choices day in and day out, the reality is that what we choose to do every day has long-term impacts on our health.

The lifestyle factors that help prevent stroke include:

• Being physically active every day
• Eating healthy (by following the Mediterranean diet, for instance)
• Maintaining a healthy weight
• Avoiding smoking, or quitting smoking if you already smoke
• Limiting alcohol and avoiding excessive alcohol use
• Seeing your doctor so you can be screened for stroke risk factors

The last step is very important, especially for young adults — who might assume they're healthy and not at risk for stroke.

"The major risk factors associated with a stroke in young people are abdominal obesity, smoking, physical inactivity and hypertension," says Dr. Vijayakumar. "By regularly being screened for these health issues, you can get help avoiding progression, or receive treatment so the problem is well managed and your stroke risk is reduced."

(Related: 5 Reasons You Need a Primary Care Doctor in Your 20s & 30s)